Suspensions of polymeric chlorotrifluoroethylene



Patented Oct. 20, 1953 UNITED STATES tears OFFICE SUSPENSIONS POLYMERIC CHLORO- TRIFLUOROETHYLENE Murray M. Sprung, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York No Drawing. Original application November 25,

1949, Serial No. 129,532. Divided and this application January 16, 1953, Serial No. 331,730

14 Claims. (Cl. 260-323) Because of its extreme chemical resistance and substantial insolubility in many of the comticularly, the invention relates to a suspension f comprising (1) a dispersed phase of finely divided polymeric chlorotrifiuoroethylene and (2) a dispersing medium comprising (a) an organic liquid or mixture of organic liquids which, at elevated temperatures but below their boiling points, are solvents for the aforementioned polymer, and (b) a liquid diluent which is a nonsolvent for the polymer at any temperature and which is an oxygen-containing compound having a boiling point above 50 C. and selected 3? from the class consisting of saturated aliphatic ethers (both straight-chained and cyclic), saturated aliphatic monohydric alcohols (including halogenated, e. g., chlorinated alcohols), alimon organic solvents, great difiiculty has been experienced in obtaining the polymeric chlorotrifluoroethylene in usable form whereby it can be employed for coating or impregnating applications. Many attempts have been made to form solutions of the polymeric chlorotrifiuoroethylene, but these attempts have generally been unsuccessful because the limit of solubility of the polymeric chlorotrifiuoroethylene in the solvent has been so small as to render it impractical.

phatic ketones, aliphatic esters, aliphatic lactones, aliphatic acetals, mixtures of monohydric saturated aliphatic alcohols and dihydric saturated aliphatic alcohols, and mixtures of all the foregoing oxygen-containing compounds. The

invention also embraces methods for making the .71

above-described suspensions.

Solid, high molecular weight, polymeric chlorotrifiuoroethylene has been found to have good heat resistance and chemical resistance and becauseiof this is eminently suitable for many applications where such properties are desired. Electrical conductors insulated with polymeric chlordtrifluoroethylene are capable of withstanding temperatures of the order of from about 150 to 200 C. for long periods of time with little change in the physical characteristics or of the insulating properties of the polymeric insula tion. Such polymeric material is also highly desired for many applications where its high softening point is an advantage. Thus, it is possible to mold various objects from the polymeric chlorotrifiuoroethylene, either with or without fillers, to give useful articles which are dimensionally stable over a wide temperature range Attempts to prepare suspensions of polymeric chlorotrifluoroethylene have also been generally unsuccessful because of the poor stability of such suspensions in the dispersing mediums employed heretofore with polymeric chlorotrifluoroethylene.

' I have now discovered for the first time that it is possible to make relatively stable suspensions of polymeric chlorotrifiuoroethylene (any solid polymer thereof may be employed) using as the suspending medium a mixture of liquids described above in the first paragraph of this application. This is done by first grinding the polymeric material, for instance, in a micropulverizer, to a fine particle size and thereafter mixing the finely divided polymer with a dispersing phase comprising a mixture of ingredients comprising (a) an organic liquid which is a solvent for the polymer at an elevated temperature but below the boiling point of the liquid and (b) an oxygen-containing compound selected from the class described previously, and finally grinding this mixture, for example, in a pebble mill or a ball mill fora time sufiicient to yield a stable, uniform suspension.

Suspensions made in accordance with my above-described method are uniformly stable over long periods of time. I am able to prepare by my method smooth, creamy suspensions which can be obtained in two to three days grinding time in standard ball mills and which are more uniform, less granular, less thixotropic, and have slower settling rates than those obtained from many other types of organic liquids. If there should be some slight settling out of the suspended polymeric material, it is possible by mere stirring, either before use or during use, to reinstate the suspension to its former acceptable state. Although some dispersions of similar polymers, e. g., polymeric tetrafiuoroethylene, have been made using other materials as a dispersing phase, nevertheless, attempts to use these particular dispersing media with polymeric chlorotrifluoroethylene have been generally unsuccessful.

Generally, the procedure followed for making my suspensions comprises pulverizing or grinding polymeric 1. chlorotrifiuoroethylene .to a fine particle size oftheorder of-about'0.2 to 25 microns, preferably 0.5 to 15 microns. This may be accomplished by grinding the polymer" in a micropulverizer used for such purposes.

Thereafter, the finely ground' polymergand*the mixture of liquids comprising the dispersingphase are mixed together. andaagaintgroundy, this time, for instance, inieitherraeball;mill.;.or1

a pebble mill. The ratio, by weight, of dispersing phase and finely divided pplymer. may be varied within wide limits 'depensding up'on the desired concentration of the final.. susp,ension.,

Thus, I may advantageously employ,'by weight, from 0.01 to 1 or more parts of the=- polymer per part of the liquid dispersing phase. A range which I have found. useful comprises, by weight, from about O-.O5 to 0.3 part polymer per part of the-liquid dispersing-V phasee. On. a percentage basis, good results may be realized whenthe polymer comprises about to .30 per cent; by Weight, of the total weight of. polymer and..the dispersing phase...

From the foregeinggeneral description it will be apparent that my invention employs both an active solvent and a -relativelyinexpensive, non.- solvent, diluent, 13111155. permitting a considerable saving in money.- The .useqof :a; dispersing phase comprising ;a mixture of-dngredients wherein. one of -.the ingredients is a solvent for the polymer .at elevated temperatures-thas several advantages. In. thefirstplace, by "usinga relativelyvolatile nonesolvent diluent inrthe-dispersing phase,-.-.this diluent flashes off first during the baking cycle when the coated object-is passed' through a :baking oven at elevated temperatures to effect fusion or coalescence-of the individual particle'of poly-- meric chlorotrifluoroethylenedeposited. on. the surface.- The active solvent -.or.solvents remai ning inthe' dispersing phasezare their able to dissolve or partially dissolve or to: plasticize tor swell the :uniformly deposited, finely divided. particles of solid, polymeric chlorotrifluoroethylene.-: Sintering or'fusiomtherefora-of the individual polymeric particles occurs at temperatures lower than are normally reouired for thepurepolymer. After fusion, the:-active:*solvents :are preferably completely removedeby: further heating:: The active (i; e., solvents-sin which'the polymer:-is soluble at elevated temperatures) 'higher, boiling solvents can be recovered by meansof "a-suitable recovery system andretain'ed for usein making additional suspensions;

The proportion" of :active solvent in the. dispersing-phase may, of course; b'e'varied within wide limits. However, .for economical reasons I have found it practical to use a minor proportion (e. g., from 5 to'49'per cent, by weight, fOI'IiI'I- stance, from 10 to 40 percent, based on the total weight of the dispersing phase) of such liquids and a major proportion (e. g.,- from-51 to 95'per cent, by weight) of the liquidnon-solvent "(1; e-., forthe polymeric -chlorotrifluoroethy1ene)' diluz triethylene glycol di- (2-ethylhexoate) ent. Variations Within these ranges, e. g., from 5 to per cent of the active solvent and from 10 to per cent of the non-solvent diluent, may be employed without departing from the scope of the invention.

The number of liquid active solvents or mixture of such material which I have found can be employed in the practice of this invention are relatively few. Among these may be mentioned, for example, certain individual alkylated, preferably liquid, aromatic hydrocarbons, for instance, pseudocumene, mesitylene, t butylbenzene,-. beta-.methylnaphthalene; para-.t-xbutyltoluene, alpha,beta-dimethylnaphthalene; amylbiphenyl, alpha,methyl,para-methylstyrene, paracymene, distyrene (styrene dimer), diamylbiphenyl, para-di-t-butylbenzene, etc.; certain high boiling; organicesters, for instance, dibutyl phthalate, dibutyl sebacate, butyl stearate, dibutyladipate, dioctyl sebacate, methyl stearate, tributyl citrate,1.tributyl tricarballylate, acetyl tributyl citrate, dihexyl tetrachlorophthalate, dioctyl .tetrachlorophthalate (including its isomers, e: g.,, di-.(2ethylhexyl) tetrachlorophthalate),

betanaphthyl benzoate, and mixtures thereof, etc; fiuorin'ated organic compounds having a boiling point above C. and selected from the class consisting of: .(dr) nuclearly fiuorinatedaromatic hydrocarbons containing two aromatic nuclei free of:other :substituents; (2).) halogenated (e. g., chlorinated, brominated, etc.) derivatives of lower? alkyl-substitutedm (e. g., methyl, ethyl, propyl, isopropyl and butyl) aromatic-hydrocarbonscontaining fluorine-(e. g.,,from 1 ,to 6 or more: fluorines); in the alkyl. substituent, (c) fiuorinated-chlorinated; aliphatic hydrocarbons of the C3 and Cr series containing at .least two chlorine:atoms:(e. g;,,.fromz2:to:.6), (d) liquid low molecular "weightipolymers of chlorotrifluo-v methylene. (known. as .Fluorolubes?) having the recurring structural unit (CF2CFC1.)1L where n is anainteger equal to :frome .to ;16, inclusive, etc. Mixtures ofJthe foregoing materials may also be employedaaswill be apparent .to:.those skilled in the-art.

Additional examples of many of'the active solvents which may be employed in the practice of my invention maybe "found in-my copending application Serial No; 129,531 and in the joint 00- pending' applications of Frederick O. Guenther and myself, Serial Nos. 129,533 and 129,534, all filed November 25, 1949, andassigned'to the same assignee as the present invention.

In order that those skilled in the art may better understand how'the present invention may bespracticed, the following'examples are given by way of illustration andnot by way of limitation. All parts are by weight.

EXAMPLE In'this example polymericchlorotrifiuoroethylene (of different no strength temperatures) in a finely'divided form wherein. the average particle size was from about 0.5 to'5 microns was mixed with a liquid dispersing medium comprising a mixture of organic liquids of which a major proportion were non-solvents for the polymer and a minor proportion were solvents for the polymer at elevated temperatures. The following table shows the ingredients employed in making the suspensions as well as the proportions ofingredients, and the time the mixture of ingredients was milled to obtain the suspen- $10118.

build-up of the insulating coating. The insulated conductors were then tested for abrasion resistance (using the method disclosed in the application of Edward J. Flynn and Gerald W. Young, Serial No. 54,636, filed October 15, 1948, and assigned to the same assignee as the present invention), insulation resistance, and dielectric strength. Thermal life measured at 250 C. was of the order of to hours. The following table showsrepresentative results of these tests.

Table 1 Weight of Weight Dispersing Milling Suspension No. Polymer, Dispersmg Phase Phase 00111- Time, Parts ponents, Days Parts Fluorolube d 98 1 175 aipha-Fluoronaphthalene 147 3 n-Butanol 580 Fluorolube 2 175 alpha-Fluoronaphtha1ene.. 210 4.7

n-Butanol v. 475 Fluorolube 98 3 175 alpha-Chloronaphthalene. 147 3 -Butanol 580 Fluorolube 98 4 175 Mesitylene 147 3 n-Butanol 580 Fluorolube 98 1 5 175 Solvesso 147 3 n-Butan01. 580 Fluorolube 98 6 l 175 alpha-Fluoronaphthalene 147 P 5 n- Butanol 580 Fluorolube 132 7 e 165 alpha-Fluoronaphthalene. 199 6. 7

11-Butauo1 504 Fluorolube 140 8 180 alpha-Fluoronaphthalener. 205 10 n-Butanol 475 Fluorolube 98 9 I 175 alpha-Ohloronaphthalene 147 6 -Butanol 580 Fluorolube 131 10 180 alpha-Ghloronaphthalene. 197 6.7

n-Bu an 492 Fluorolube 98 11 n 175 Mcsitylene. 147 5 n-Butanol. 580 Fluorolubefln 9O 12 e Hexachlorobutadiene 135 5 -Butanol 615 Fluorolubc 132 13 alpha-Fluoronaphthalene. 199 4 -Hexanol 504 V Fluorolube 132 14 e 165 alpha-Fluoronaphthalene. 199 4 Z-Ethylhexanol 504 Fluorolube 132 15 b 165 {a1pha-Fluoronaphthalene. 199 5.7

-Butanol 504 Fluorolube 98 16 Vlesitylene 147 5 n-ButanoL 5 -0 Fluorolubc... 1.00 17 b 150 t-Butyl benzene. 160 4. 8

n-Butanol. 600 Fluoroluba. 111 18 300 alpha-Fluoronaphthalene.. 167 3 n-Butanol 422 The polymer employed in suspensions Nos. 1 to 5 had a nofistrength temperature of about 245 C.

h No strength temperature of about 270C b No strength temperature of about 305 C. B This polymer was more finely divided than any of the three other polymers employed above and had a no strength temperature of about 220 C.

d Low molecular weight polymer of chlorotrifiuoroethylone and more particularly described in my copending application Serial No. 129,534.

The suspensions prepared above were all Table II smooth, homogeneous and quite stable. In order to test the effect of using these suspensions Abrasion Insulation Dielectric Bum U as coatings for electrical conductors, a 32-m1l1 51151101190111 Reslstame Resistance Strength Mi]5 55 Strokes InMercury (kv.) copper wire containlng an outside thin layer of plated cadmium was passed through each sus- 7 w 0 9 2 8 pension and thereafter into a vertlcal oven (the 14 a M 22 effective heated section was about three feet in Z height) maintained at an air temperature of 7 an L9 25 about 350 to 425 C. The speed with which the $2 2 conductor was passed through the suspension 4 m 1, and the oven varied from about thirty seconds 3 2 to approximately sixty seconds per pass. Each 22 m 25 M conductor was passed through the suspenslon and 1 the oven five tlmes in order to insure a good It will, of course, be apparent to those skilled in the art that in addition to the compositions described above, other concentrations of polymeric chlorotrifluoroethylene in the suspensicn may be employed Without departing from the scope of the invention. The various ratios of ingredients which can be advantageously employed have been disclosed previously.

In addition to the active solvents employed .17 above, other such materials may also be used, many examples of such solvents being more particularly disclosed in my aforementioned applications filed concurrently herewith, which by reference are made part of the disclosuresin the instant application.

In addition to the known non-solvent diluents employed in the examples above, I may use other oxygen-containing compounds having a boiling point above 50 C. and selected from the class of compounds mentioned in the first paragraph of this specification. Among such compounds may be mentioned, for instance, aliphatic ethers (e. g., diisopropyl ether, di-n-butyl ether, dioxane, tetrahydrofurane, 1,2-di-n-butoxy ethane, etc.) aliphatic monohydric alcohols (e. g., isobutyl alcohol, n-amyl alcohol, isoamyl alcohol, tertiary amyl alcohol, 2-ethylhexanol, chlorohydrin, etc.); saturated aliphatic esters (e. g., methyl acetate, ethyl acetate, ethylene glycol acetate, chloroethyl acetate, beta-methoxyethyl acetate, methyl lactate, etc); aliphatic ketones (e. g., actone, methyl ethyl ketone, methyl-npropyl ketone, diacetone, etc); aliphatic acetal-s (e. g., dimethyl acetal, 1,3-diox0lane, dichloromethyl formal, bis-beta-methoxyethyl formal, etc.) aliphatic lactones (e. g., gamma-butyrolactone, alpha-methyl, gamma-valerolactone, etc); mixtures of saturated aliphatic monohydric alcohols and dihydric aliphatic alcohols (e. g., ine

cluding the saturated aliphatic monohydric alcohols mentioned above mixed with, for instance, ethylene glycol, trimethylene glycol, tetramethylene glycol, 2-methyl-2-,4-pentanediol, dipropylene glycol, etc). Mixtures of any of the foregoing known solvent diluents may also be employed if desired. Many of the foregoing oxygencontaining compounds, as well as other such compounds and proportions of ingredients including the ratio of dihydric to monohydric alco- I hol which may be employed in the practice of the present invention, are more particularly disclosed in my application Serial No. 129,535 filed November 25, 1949, and assigned to the same assignee as the present invention.

Advantageously, the limit of the number of compounds, both non-solvent and solvent components, is dependent on the limits of miscibility of the components involved in the dispersing phase. Little difliculty has been encountered in using any of the non-solvent components with the solvent components in the dispersing phase.

In general, it is desirable to grind the pulverized solidpolymer with the liquid mixture, comprising the dispersing phase in a ball mill for several days. However, for purposesof successful application to magnet Wire, it may not be necessary to grind for more than 24 to "72 hours, provided the original polymer has been reduced to the order of magnitude of at least 0.2 to 25 microns average particle size before grinding. No heating is necessary at any time for making the suspensions. The time required for ball-mill grinding to give a satisfactory stable suspension may range from about one-half to 15 days or more and, advantageously, in the case of the examples described above, from about 1 to 10 days.

The suspensions of polymeric chlorotrifluoroethylene described above may be employed in various ways. They may be used for coating and impregnating various fillers such as, for example, glass cloth, glass batting, asbestos cloth, mica, .etc. If desired, the suspensions may be advantageously employedin making molding compositicns-by addmgtothe suspension'various inert inorganic fillersto obtain a homogeneous mixture and thereafter removing the solvent and non-solvent (i. e., oxygen-containing) components of the dispersing phase from the mixture. Laminated products may also be prepared by coating and impregnating sheet :material and superposing layers of the impregnated and coated material and pressing the total assembly under heat and pressure toobtain fusing of the polymer and to give a homogeneous article. In some coating applications as, for instance, in the coating of electrical conductors, such as magnet wire, it has been found advantageous to add varying amounts, for example, from one to ten per cent, by Weight, .or more of a finely ground pigment or filler to the suspensions. Among such pigments and fillers which may be employed are, .for example, .catalpa clay, bentonite, mica dust, titanium dioxide, silica, lead silicate, lead titanate, etc.

My claimed suspensions containingactive solvents are relatively easy to use, and give products having good appearance and a high degree of clarity. Films (e. g., from polymers having no strength temperatures of from 240 to 270 C.) deposited from these suspensions on glass, for example, were clear, completely fused, continuous, and strongly adherent at a maximum fusion temperature of 260 C.

The suspensions herein described have been found to be eminently suitable for treating terratex (bentonite-asbestos films) for increasing the strength of the latter. More particularly, the strength of terratex, which normally has a tensile of about 240 to 300p. s. i. was improved to a crosswise tensile strength of 1,000 p. s. i. and a lengthwise tensile strength of 1400 p. s. i. when about 52%, by weight, polymer based on the weight of the terratex, was added by dipping the terratex in the suspension and baking in an oven.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A liquid suspension comprising a dispersed phase consisting essentially of finely divided, solid, high molecularweight polychlorotrifluoroethylene and a dispersing medium for the solid polychlorotrifiuoroethylene comprising (1) an organic liquid which is a solvent for the aforesaid solid polymer at elevated temperatures but whose solvent characteristics are eifective at temperatures below the boiling points of the liquid, the aforementioned liquid being selected from the class consisting .of pseudocumene, mesitylene, t-butylbenzene, beta-methylnaphthalene, para-t-butyltoluene, alpha, beta-dimethylnaphthalene, amylbiphenyl, alpha-methyl para-methylstyrene, para-cymene, distyrene, diamylbiphenyl, and para-di-t-butylbenzene, and (2) a non-solvent liquid oxygen-containing diluent having a boiling point above 50 C. and selected from the class consisting of saturated aliphatic ethers, saturated aliphatic monohydric alcohols, saturated aliphatic ketones, saturated aliphatic esters, mixtures of monohydric saturated aliphatic alcohols and dihydric saturated aliphatic alcohols, and mixtures of the foregoing oxygen-containing compounds.

.2. A liquid suspension comprising a dispersed phase consisting essentially of finely divided, solid, high molecular weight polychlorotrifiuoroethylene and a dispersing medium for the solid polychlorotrifiuoroethylene comprising (1) .mesityleneand (2) n-butanol.

.3. A liquid suspension comprising a dispersed phase consisting essentially of finely divided,

solid, high molecular weight polychlorotrifiuoroethylene and a dispersing medium for the solid polychlorotrifluoroethylene comprising (1) mesitylene and (2) a liquid saturated aliphatic monohydric alcohol boiling above 50 C.

4. A liquid suspension comprising a dispersed phase consisting essentially of finely divided, solid, high molecular weight polychlorotrifluoroethylene and a dispersing medium for the solid polychlorotrifiuoro-ethylene comprising (1) mesitylene and (2) a liquid saturated aliphatic ether boiling above 50 C.

5. A liquid suspension comprising a dispersed phase consisting essentially of finely divided, solid, high molecular weight polychlorotrifluoroethylene and a dispersing medium for the solid polychlorotrifiuoroethylene comprising (1) mesitylene and (2) a liquid saturated aliphatic acetal boiling above 50 C.

6. A liquid suspension comprising a dispersed phase consisting essentially of finely divided,.

solid, high molecular weight polychlorotrifluoroethylene and a dispersing medium for the solid po-lyohlorotrifiuoroethylene comprising (1) mesitylene and (2) a liquid saturated aliphatic ketone boiling above 50 C.

7. A liquid suspension comprising a dispersed phase consisting essentially of finely divided, solid, high molecular weight polychlorotrifluoroethylene as the sole solid polymeric ingredient and a dispersing medium for the solid polychlorotrifluoroethylene comprising (1) mesitylene and (2) a mixture of a liquid monohydric saturated aliphatic alcohol and a liquid dihydric saturated aliphatic alcohol, both of the aforesaid alcohols boiling above 50 C.

8. The method of making a stable suspension which comprises (1) forming a mixture of ingredients comprising (a) finely divided, solid, high molecular weight polychlorotrifiuoroethylene and (b) a dispersing medium for (a) comprising (A) an organic liquid which is a solvent for the aforesaid solid polymer at elevated temperatures but whose solvent characteristics are effective at a temperature below the boiling point of the liquid, the aforementioned liquid being selected from the class consisting of pseudocumene,

mesitylene, t-butylbenzene, beta-methyl-naphthalene, para-t-butyltoluene, alpha,beta-dimethylnaphthalene, amylbiphenyl, alpha-methyl paramethylstyrene, para-oymene, distyrene, diamylbiphenyl, and para-di-t-butylbenzene, and (B) a non-solvent liquid oxygen-containing diluent having a boiling point above 50 C. and selected from the class consisting of saturated aliphatic ethers, saturated aliphatic monohydric alcohols, saturated aliphatic ketones, saturated aliphatic esters, mixtures of monohydric saturated aliphatic alcohols and dihydric saturated aliphatic alcohols, and mixtures of the foregoing oxygencontaining compounds, and (2) grinding the aforementioned mixture of ingredients until a stabl suspension is obtained.

9. The method of making a stable suspension which comprises (1) forming a mixture of ingredients comprising (a) finely divided, solid, high molecular weight polychlorotrifluoroethylene and (b) a dispersing medium for (a) comprising (A) mesitylene and (B) n-butanol, and (2) grinding the aforementioned mixture of ingredients until a stable suspension is obtained.

10. The method of making a stable suspension which comprises (1) forming a mixtur of ingredients comprising (a) finely divided, solid, high molecular weight polychlorofiuoroethylene and (b) a dispersing medium for (a) comprising (A) mesitylene and (B) a liquid saturated aliphatic monohydric alcohol boiling above 50 C. and (2) grinding the aforementioned mixture of ingredients until a stable suspension is obtained.

11. The method of making a stable suspension which comprises (1) forming a mixtur of ingredients comprising (a) finely divided, solid, high molecular Weight polychlorotrifiuoroethylene and (b) a dispersing medium for (a) comprising (A) mesitylene and (B) a liquid saturated aliphatic ether boiling above 50 C., and (2) grinding the aforementioned mixture of ingredients until a stable suspension is obtained.

12. The method of making a stabl suspension which comprises (1) forming a mixture of ingredients comprising (a) finely divided, solid, high molecular weight polychlorotrifiuoroethylene and (b) a dispersing medium for (a) comprising (A) mesitylene and (B) a liquid saturated aliphatic acetal boiling above 50 C., and grinding the aforementioned mixture of ingredients until a stable suspension is obtained.

13. The method of making a stable suspension which comprises (1) forming a mixtur of ingredients comprising (a) finely divided, solid, high molecular weight polychlorotrifiuoroethylene and (b) a dispersing medium for (a) comprising (A) mesitylene and (B) a liquid saturated aliphatic ketone boiling above 50 C., and (2) grinding the aforementioned mixture of ingredients until a stable suspension is obtained.

14. The method of making a stable suspension which comprises (1) forming a mixture of ingredients comprising (a) finely divided, solid, high molecular weight polychlorotrifiuoroethylene as the sole polymeric ingredient in the solid state and (b) a dispersing medium for (a) comprising (A) mesitylene and (B) a liquid mixture of a monohydric saturated aliphatic alcohol and a dihydric saturated aliphatic alcohol, both of the aforesaid alcohols boiling above 50 C. and (2) grinding the aforementioned mixture of ingredients until a stable suspension is obtained.

MURRAY M. SPRUNG.

No references cited. 

1. A LIQUID SUSPENSION COMPRISING A DISPERSED PHASE CONSISTING ESSENTIALLY OF FINELY DIVIDED, SOLID, HIGH MOLECULAR WEIGHT POLYCHLOROTRIFLUOROETHYLENE AND A DISPERSING MEDIUM FOR THE SOLID POLYCHLOROTRIFLUOROETHYLENE COMPRISING (1) AN ORGANIC LIQUID WHICH IS A SOLVENT FOR THE AFORESAID SOLID POLYMER AT ELEVATED TEMPERATURES BUT WHOSE SOLVENT CHARACTERISTICS ARE EFFECTIVE AT TEMPERATURES BELOW THE BOILING POINTS OF THE LIQUID, THE AFOREMENTIONED LIQUID BEING SELECTED FROM THE CLASS CONSISTING OF PSEUDOCUMENE, MESITYLENE, T-BUTYLBENZENE, BETA-METHYLNAPHTHALENE, PARA-T-BUTYLTOLUENE, ALPHA, BETA-DIMETHYLNAPHTHALENE, AMYLBIPHENYL, ALPHA-METHYL PARA-METHYLSTYRENE, PARA-CYMENE, DISTYRENE, DIAMYLBIPHENYL, AND PARA-DI-T-BUTYLBENZENE, AND (2) A NON-SOLVENT LIQUID OXYGEN-CONTAINING DILUENT HAVING A BOILING POINT ABOVE 50* C. AND SELECTED FROM THE CLASS CONSISTING OF SATURATED ALIPHATIC ESTERS, SATURATED ALIPHATIC MONOHYDRIC ALCOHOLS, SATURATED ALIPHATIC KETONES, SATURATED ALIPHATIC ESTERS, MIXTURES OF MONOHYDRIC SATURATED ALIPHATIC ALCOHOLS AND DIHYDRIC SATURATED ALIPHATIC ALCOHOLS, AND MIXTURES OF THE AFOREGOING OXYGEN-CONTAINING COMPOUNDS. 